This post aims to bring you up to speed on whats out there, in regards to ease administration of the VMware Virtual Infrastructure.
Since i'm lazy and dont like doing the same thing twize, a lot of these "tools" are based on scripting since its the road to automation (and perhaps freedom?)

VMware: VI Toolkit (For Windows)
This should be installed everywhere! (where you have VI that is) It extends on Windows PowerShell, which in turn also makes it require .NET FrameWork 2.0 and ...you guessed it - PowerShell!
A set of CMD-lets are installed which makes a lot of things way easier, instead of using the sometime dreadfull VI client.

Get-VMHost | Get-VMHostStorage -RescanAllHBA

The above task makes for a nice hell'ish experience if done manual. with VI Toolkit its just a simple one-liner.
For more examples, check out the public available LAB manual from VMworld Europe 2008

If you are just getting started using Powershell, this post from Jakob H. Heidelberg basically lists all you need for getting started. For more VI toolkit specific examples,
check out Hugo Peeters blog at http://www.peetersonline.nl/. Thats world class VI Toolkit examples right there!

There's a new version on the way, which builds in the PowerShell 2.0. (Currently CTP) New CMD-lets are to be expected, but the really cool thing will be the Community Extensions.
It's going to make new functionallity really fast to develop, and at the same time easy to make available to the public.
To have a read at that, head over to the project site, and the VMware official VI Toolkit blog for more information.

VI Toolkit is all great, but what would be even greater was if you could run those nifty scripts directly from the VI client. Well you can - icomasoft VI PowerScripter.
Currently Beta 2 does exactly that. Its a plug-in for the VI client, and adds easy to use right-click options for running scripts.
This really adds to the user experience, especially if you have admins who get all crazy and hostile if you mention CLI and scripting. Give it at go at icomasoft http://www.icomasoft.com/products/vi-powerscripter.html
There are also script examples available, so you can get a taste of the functionallaty right out of the box. PowerScripter sample scripts.

That sounds nice, but how on earth do i write all these glowing lines of code to save mankind you might ask? PowerGUI comes to mind. It lets you see PowerShell output in a GUI, without having to dive into the dark corners of the command line. It also includes a really nice editor, which makes it somewhat easier to develop scripts compared to using notepad.
PowerPacks is where it gets really good (besides being free-of-charge, by Quest Software). PowerPacks are add-ons to the PowerGUI, and currently supports stuff like Vmware VI, Exchange 2007, Hyper-V, Operations Manager and so on.
For a complete list, and download of the program check out http://powergui.org/
Personally i also use another editor, called Primalscript Enterprise (By SAPIEN technologies). It's however not freeware, but it makes for one hell of a program if you are all about vbscript, PS, perl etc.
Trial versions are available at http://www.primalscript.com/
UltraEdit, TextPad, Notepad++ are some amongst other tools you might want to check out before settling on the above mentioned.

VMware Infrastructure Remote Command Lince Interface (RCLI)
Most people learn about the RCLI when they want to use Storage Vmotion. There are however other things to the RCLI then svmotion.pl. Its a collection of perl scripts which add some of the same functionality available in the COS.
It's also the only way to go COS-wannabe if you have ESXi in your environment. The RCLI package comes with approx 25-30 scripts to get you started, and these have roots in the esxcfg- and other COS related commands.
You can download the RCLI here, and ther is also a full documentation on the included scripts.

CLI might be your best friend in a lot of situations, but when it comes to using Storage Vmotion, it just doesn't hold up. The first ever 3rd party VI plug-in made a nice integration for using Storage Vmotion as it was ment to be used. SVMotion plugin by "akutz" is one of the more usefull plug-ins out there. This is really a plug-in you should always install to your VI client, and its the way VMware should have implemented Svmotion usage to begin with.

Backup made easy: VizionCore vRangerPRO:
This is a really cool program, which makes backup of VMs a joy to work with. If i'm at a small customer, i almost always point them to buy vRangerPRO since it makes the backup process so much easier. Even if you already have a backup program, which can piggy-bag VCB, chances are vRangerPRO makes the backup process easier and more flawless. You can download a trial version - give it a try, im sure you'll like it!

Accessing your ESX servers:
Say COS and chances are someone will stand up and yell: PuTTY! Thats my most beloved tool for connecting to ESX servers, free and easy to use with a lot of features.

When dealing with files on the ESX servers WinSCP could be worth checking out. Its a SFTP and FTP client for windows, which is really handy when working with files on ESX servers.

Copying files over SCP is not the fastest thing in the world. If you are uploading big ISO files, vmdk or whatever big files, Veeam FastSCP is your best friend. Dont know how it works, but its way faster then WinSCP when dealing with large files.

I'll update this post whenever i stumple upon something new which goes into my VI toolbox, and the things i have missed - please feel free to post those in comments:)